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in the usual manner； and to draw a fresh supply of gas from
further cylinders when the occasion arises for re…inflation。
Although the familiar spherical balloon has proved perfectly
adequate for reconnoitring in the British and French armies； the
German authorities maintained that it was not satisfactory in
anything but calm weather。 Accordingly scientific initiative was
stimulated with a view to the evolution of a superior vessel。
These endeavours culminated in the Parseval…Siegsfeld captive
balloon； which has a quaint appearance。 It has the form of a
bulky cylinder with hemispherical extremities。 At one end of the
balloon there is a surrounding outer bag； reminiscent of a
cancerous growth。 The lower end of this is open。 This
attachment serves the purpose of a ballonet。 The wind blowing
against the opening； which faces it； charges the ballonet with
air。 This action； it is claimed； serves to steady the main
vessel； somewhat in the manner of the tail of a kite； thereby
enabling observations to be made as easily and correctly in rough
as in calm weather。 The appearance of the balloon while aloft is
certainly curious。 It appears to be rearing up on end； as if the
extremity saddled with the ballonet were weighted。
British and French captive balloon authorities are disposed to
discount the steadying effect of this attachment； and； indeed； to
maintain that it is a distinct disadvantage。 It may hold the
vessel steadier for the purpose of observation； but at the same
time it renders the balloon a steadier target for hostile fire。
On the other hand； the swaying of a spherical balloon with the
wind materially contributes to its safety。 A moving object；
particularly when its oscillations are irregular and
incalculable； is an extremely difficult object at which to take
effective aim。
Seeing that even a small captive balloon is of appreciable
dimensionsfrom 25 to 33 feet or more in diameterone might
consider it an easy object to hit。 But experience has proved
otherwise。 In the first place the colour of the balloon is
distinctly protective。 The golden or yellowish tinge harmonises
well with the daylight； even in gloomy weather； while at
night…time it blends excellently with the moonlight。 For
effective observations a high altitude is undesirable。 At a
height of 600 feet the horizon is about 28 miles from the
observer； as compared with the 3 miles constituting the range of
vision from the ground over perfectly flat country。 Thus it will
be seen that the 〃spotter〃 up aloft has the command of a
considerable tract。
Various ways and means of finding the range of a captive balloon
have been prepared； and tables innumerable are available for
committal to memory； while those weapons especially designed for
aerial targets are fitted with excellent range…finders and other
instruments。 The Germans； with characteristic thoroughness； have
devoted considerable attention to this subject； but from the
results which they have achieved up to the present this guiding
knowledge appears to be more spectacular and impressive than
effective。
To put a captive balloon out of action one must either riddle the
envelope； causing it to leak like a sieve； blow the vessel to
pieces； or ignite the highly inflammable gas with which it is
inflated。 Individual rifle fire will inflict no tangible damage。
A bullet； if it finds its billet； will merely pass through the
envelope and leave two small punctures。 True； these vents will
allow the gas to escape； but this action will proceed so slowly
as to permit the vessel to remain aloft long enough to enable the
observer to complete his work。 A lucky rifle volley； or the
stream of bullets from a machine gun may riddle the envelope；
precipitating a hurried descent； owing to the greater number of
perforations through which the gas is able to escape； but as a
rule the observer will be able to land safely。
Consequently the general practice is to shatter the aerostat； and
to this end either shrapnel； high explosive； or incendiary shells
will be used。 The former must explode quite close to the balloon
in order to achieve the desired end； while the incendiary shell
must actually strike it； so as to fire the gas。 The high
explosive shell may explode effectually some feet away from the
vessel； inasmuch as in this instance dependence is placed upon
the terrific concussion produced by the explosion which； acting
upon the fragile fabric of the balloon； brings about a complete
collapse of the envelope。 If a shrapnel is well placed and
explodes immediately above the balloon； the envelope will be torn
to shreds and a violent explosion of the gas will be precipitated。
But as a matter of fact； it is extremely difficult to place a
shrapnel shell so as to consummate this end。 The range is not
picked up easily； while the timing of the fuse to bring about the
explosion of the shell at the critical moment is invariably a
complex problem。
One favourite method of finding the range of a balloon is shown
in the accompanying diagrams。 The artillery battery is at B
and the captive balloon； C； is anchored at A。 On either
side of B and at a specified distance； observers O1 and O2
respectively are stationed。 First a shell is fired at 〃long〃
range； possibly the maximum range of the gun。 It bursts at D。
As it has burst immediately in the line of sight of B； but with
the smoke obscured by the figure of the balloon C； it is obvious
to B that the explosion has occurred behind the objective； but at
what distance he cannot tell。 To O1 and O2；however； it is seen
to have burst at a considerable distance behind C though to the
former it appears to have burst to the left and to the second
observer to the right of the target。
Another shell； at 〃short〃 range； is now fired； and it bursts at
E。 The explosion takes place in the line of sight of B； who
knows that he has fired short of the balloon because the latter
is eclipsed by the smoke。 But the two observers see that it is
very short； and here again the explosion appears to O1 to have
occurred to the right of the target； while to O2 it has evidently
burst to the left of the aerostat； as revealed by the relation of
the position of the balloon to the bursting of the shell shown in
Fig。 3。
A third round is fired； and the shell explodes at F。 In this
instance the explosion takes place below the balloon。 Both the
observers and the artillery man concur in their deductions upon
the point at which the shell burst。 But the shell must explode
above the balloon； and accordingly a fourth round is discharged
and the shell bursts at G。
This appears to be above the balloon； inasmuch as the lines of
sight of the two observers and B converge at this point。 But
whether the explosion occurs immediately above the vessel as is
desired； it is impossible to say definitely； because it may
explode too far behind to be effective。 Conse